command: convert command_return to to a strictly-typed enum

25 files changed, 429 insertions, 422 deletions

diff --git a/Makefile.am b/Makefile.am
index 519748812..a766704c0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -54,7 +54,6 @@ src_mpd_LDADD = \
 
 mpd_headers = \
 	src/check.h \
-	src/command.h \
 	src/gerror.h \
 	src/TextInputStream.hxx \
 	src/AudioCompress/config.h \
@@ -79,6 +78,7 @@ src_mpd_SOURCES = \
 	src/protocol/Ack.cxx src/protocol/Ack.hxx \
 	src/protocol/ArgParser.cxx src/protocol/ArgParser.hxx \
 	src/protocol/Result.cxx src/protocol/Result.hxx \
+	src/CommandResult.hxx \
 	src/CommandError.cxx src/CommandError.hxx \
 	src/AllCommands.cxx src/AllCommands.hxx \
 	src/QueueCommands.cxx src/QueueCommands.hxx \
diff --git a/src/AllCommands.cxx b/src/AllCommands.cxx
index 95edb0f19..2271aeff2 100644
--- a/src/AllCommands.cxx
+++ b/src/AllCommands.cxx
@@ -19,7 +19,6 @@
 
 #include "config.h"
 #include "AllCommands.hxx"
-#include "command.h"
 #include "QueueCommands.hxx"
 #include "PlayerCommands.hxx"
 #include "PlaylistCommands.hxx"
@@ -56,14 +55,14 @@ struct command {
 	unsigned permission;
 	int min;
 	int max;
-	enum command_return (*handler)(Client &client, int argc, char **argv);
+	CommandResult (*handler)(Client &client, int argc, char **argv);
 };
 
 /* don't be fooled, this is the command handler for "commands" command */
-static enum command_return
+static CommandResult
 handle_commands(Client &client, int argc, char *argv[]);
 
-static enum command_return
+static CommandResult
 handle_not_commands(Client &client, int argc, char *argv[]);
 
 /**
@@ -178,7 +177,7 @@ command_available(gcc_unused const struct command *cmd)
 }
 
 /* don't be fooled, this is the command handler for "commands" command */
-static enum command_return
+static CommandResult
 handle_commands(Client &client,
 		gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -193,10 +192,10 @@ handle_commands(Client &client,
 			client_printf(client, "command: %s\n", cmd->cmd);
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-static enum command_return
+static CommandResult
 handle_not_commands(Client &client,
 		    gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -210,7 +209,7 @@ handle_not_commands(Client &client,
 			client_printf(client, "command: %s\n", cmd->cmd);
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
 void command_init(void)
@@ -308,13 +307,13 @@ command_checked_lookup(Client &client, unsigned permission,
 	return cmd;
 }
 
-enum command_return
+CommandResult
 command_process(Client &client, unsigned num, char *line)
 {
 	Error error;
 	char *argv[COMMAND_ARGV_MAX] = { nullptr };
 	const struct command *cmd;
-	enum command_return ret = COMMAND_RETURN_ERROR;
+	CommandResult ret = CommandResult::ERROR;
 
 	command_list_num = num;
 
@@ -333,7 +332,7 @@ command_process(Client &client, unsigned num, char *line)
 
 		current_command = nullptr;
 
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	unsigned argc = 1;
@@ -353,13 +352,13 @@ command_process(Client &client, unsigned num, char *line)
 	if (argc >= COMMAND_ARGV_MAX) {
 		command_error(client, ACK_ERROR_ARG, "Too many arguments");
 		current_command = nullptr;
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	if (!tokenizer.IsEnd()) {
 		command_error(client, ACK_ERROR_ARG, "%s", error.GetMessage());
 		current_command = nullptr;
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	/* look up and invoke the command handler */
diff --git a/src/AllCommands.hxx b/src/AllCommands.hxx
index 4ab69755a..2be94c136 100644
--- a/src/AllCommands.hxx
+++ b/src/AllCommands.hxx
@@ -20,7 +20,7 @@
 #ifndef MPD_ALL_COMMANDS_HXX
 #define MPD_ALL_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
@@ -28,7 +28,7 @@ void command_init(void);
 
 void command_finish(void);
 
-enum command_return
+CommandResult
 command_process(Client &client, unsigned num, char *line);
 
 #endif
diff --git a/src/ClientInternal.hxx b/src/ClientInternal.hxx
index 4df58eee6..e0affb045 100644
--- a/src/ClientInternal.hxx
+++ b/src/ClientInternal.hxx
@@ -22,7 +22,7 @@
 
 #include "check.h"
 #include "Client.hxx"
-#include "command.h"
+#include "CommandResult.hxx"
 
 enum {
 	CLIENT_MAX_SUBSCRIPTIONS = 16,
@@ -35,7 +35,7 @@ extern int client_timeout;
 extern size_t client_max_command_list_size;
 extern size_t client_max_output_buffer_size;
 
-enum command_return
+CommandResult
 client_process_line(Client &client, char *line);
 
 #endif
diff --git a/src/ClientProcess.cxx b/src/ClientProcess.cxx
index 808599ac6..39040f319 100644
--- a/src/ClientProcess.cxx
+++ b/src/ClientProcess.cxx
@@ -29,11 +29,11 @@
 #define CLIENT_LIST_OK_MODE_BEGIN "command_list_ok_begin"
 #define CLIENT_LIST_MODE_END "command_list_end"
 
-static enum command_return
+static CommandResult
 client_process_command_list(Client &client, bool list_ok,
 			    std::list<std::string> &&list)
 {
-	enum command_return ret = COMMAND_RETURN_OK;
+	CommandResult ret = CommandResult::OK;
 	unsigned num = 0;
 
 	for (auto &&i : list) {
@@ -42,7 +42,7 @@ client_process_command_list(Client &client, bool list_ok,
 		FormatDebug(client_domain, "process command \"%s\"", cmd);
 		ret = command_process(client, num++, cmd);
 		FormatDebug(client_domain, "command returned %i", ret);
-		if (ret != COMMAND_RETURN_OK || client.IsExpired())
+		if (ret != CommandResult::OK || client.IsExpired())
 			break;
 		else if (list_ok)
 			client_puts(client, "list_OK\n");
@@ -51,10 +51,10 @@ client_process_command_list(Client &client, bool list_ok,
 	return ret;
 }
 
-enum command_return
+CommandResult
 client_process_line(Client &client, char *line)
 {
-	enum command_return ret;
+	CommandResult ret;
 
 	if (strcmp(line, "noidle") == 0) {
 		if (client.idle_waiting) {
@@ -67,14 +67,14 @@ client_process_line(Client &client, char *line)
 		   has already received the full idle response from
 		   client_idle_notify(), which he can now evaluate */
 
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	} else if (client.idle_waiting) {
 		/* during idle mode, clients must not send anything
 		   except "noidle" */
 		FormatWarning(client_domain,
 			      "[%u] command \"%s\" during idle",
 			      client.num, line);
-		return COMMAND_RETURN_CLOSE;
+		return CommandResult::CLOSE;
 	}
 
 	if (client.cmd_list.IsActive()) {
@@ -92,11 +92,11 @@ client_process_line(Client &client, char *line)
 				    "[%u] process command "
 				    "list returned %i", client.num, ret);
 
-			if (ret == COMMAND_RETURN_CLOSE ||
+			if (ret == CommandResult::CLOSE ||
 			    client.IsExpired())
-				return COMMAND_RETURN_CLOSE;
+				return CommandResult::CLOSE;
 
-			if (ret == COMMAND_RETURN_OK)
+			if (ret == CommandResult::OK)
 				command_success(client);
 
 			client.cmd_list.Reset();
@@ -107,18 +107,18 @@ client_process_line(Client &client, char *line)
 					      "is larger than the max (%lu)",
 					      client.num,
 					      (unsigned long)client_max_command_list_size);
-				return COMMAND_RETURN_CLOSE;
+				return CommandResult::CLOSE;
 			}
 
-			ret = COMMAND_RETURN_OK;
+			ret = CommandResult::OK;
 		}
 	} else {
 		if (strcmp(line, CLIENT_LIST_MODE_BEGIN) == 0) {
 			client.cmd_list.Begin(false);
-			ret = COMMAND_RETURN_OK;
+			ret = CommandResult::OK;
 		} else if (strcmp(line, CLIENT_LIST_OK_MODE_BEGIN) == 0) {
 			client.cmd_list.Begin(true);
-			ret = COMMAND_RETURN_OK;
+			ret = CommandResult::OK;
 		} else {
 			FormatDebug(client_domain,
 				    "[%u] process command \"%s\"",
@@ -128,11 +128,11 @@ client_process_line(Client &client, char *line)
 				    "[%u] command returned %i",
 				    client.num, ret);
 
-			if (ret == COMMAND_RETURN_CLOSE ||
+			if (ret == CommandResult::CLOSE ||
 			    client.IsExpired())
-				return COMMAND_RETURN_CLOSE;
+				return CommandResult::CLOSE;
 
-			if (ret == COMMAND_RETURN_OK)
+			if (ret == CommandResult::OK)
 				command_success(client);
 		}
 	}
diff --git a/src/ClientRead.cxx b/src/ClientRead.cxx
index 956f4f71b..2bb3c56c0 100644
--- a/src/ClientRead.cxx
+++ b/src/ClientRead.cxx
@@ -40,19 +40,19 @@ Client::OnSocketInput(void *data, size_t length)
 
 	BufferedSocket::ConsumeInput(newline + 1 - p);
 
-	enum command_return result = client_process_line(*this, p);
+	CommandResult result = client_process_line(*this, p);
 	switch (result) {
-	case COMMAND_RETURN_OK:
-	case COMMAND_RETURN_IDLE:
-	case COMMAND_RETURN_ERROR:
+	case CommandResult::OK:
+	case CommandResult::IDLE:
+	case CommandResult::ERROR:
 		break;
 
-	case COMMAND_RETURN_KILL:
+	case CommandResult::KILL:
 		Close();
 		main_loop->Break();
 		return InputResult::CLOSED;
 
-	case COMMAND_RETURN_CLOSE:
+	case CommandResult::CLOSE:
 		Close();
 		return InputResult::CLOSED;
 	}
diff --git a/src/CommandError.cxx b/src/CommandError.cxx
index f22ad10de..fe9d9481a 100644
--- a/src/CommandError.cxx
+++ b/src/CommandError.cxx
@@ -29,66 +29,66 @@
 #include <assert.h>
 #include <errno.h>
 
-enum command_return
+CommandResult
 print_playlist_result(Client &client, PlaylistResult result)
 {
 	switch (result) {
 	case PlaylistResult::SUCCESS:
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 
 	case PlaylistResult::ERRNO:
 		command_error(client, ACK_ERROR_SYSTEM, "%s",
 			      g_strerror(errno));
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::DENIED:
 		command_error(client, ACK_ERROR_PERMISSION, "Access denied");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::NO_SUCH_SONG:
 		command_error(client, ACK_ERROR_NO_EXIST, "No such song");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::NO_SUCH_LIST:
 		command_error(client, ACK_ERROR_NO_EXIST, "No such playlist");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::LIST_EXISTS:
 		command_error(client, ACK_ERROR_EXIST,
 			      "Playlist already exists");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::BAD_NAME:
 		command_error(client, ACK_ERROR_ARG,
 			      "playlist name is invalid: "
 			      "playlist names may not contain slashes,"
 			      " newlines or carriage returns");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::BAD_RANGE:
 		command_error(client, ACK_ERROR_ARG, "Bad song index");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::NOT_PLAYING:
 		command_error(client, ACK_ERROR_PLAYER_SYNC, "Not playing");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::TOO_LARGE:
 		command_error(client, ACK_ERROR_PLAYLIST_MAX,
 			      "playlist is at the max size");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case PlaylistResult::DISABLED:
 		command_error(client, ACK_ERROR_UNKNOWN,
 			      "stored playlist support is disabled");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	assert(0);
-	return COMMAND_RETURN_ERROR;
+	return CommandResult::ERROR;
 }
 
-enum command_return
+CommandResult
 print_error(Client &client, const Error &error)
 {
 	assert(error.IsDefined());
@@ -101,24 +101,24 @@ print_error(Client &client, const Error &error)
 	} else if (error.IsDomain(ack_domain)) {
 		command_error(client, (ack)error.GetCode(),
 			      "%s", error.GetMessage());
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	} else if (error.IsDomain(db_domain)) {
 		switch ((enum db_error)error.GetCode()) {
 		case DB_DISABLED:
 			command_error(client, ACK_ERROR_NO_EXIST, "%s",
 				      error.GetMessage());
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 
 		case DB_NOT_FOUND:
 			command_error(client, ACK_ERROR_NO_EXIST, "Not found");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 	} else if (error.IsDomain(errno_domain)) {
 		command_error(client, ACK_ERROR_SYSTEM, "%s",
 			      g_strerror(error.GetCode()));
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	command_error(client, ACK_ERROR_UNKNOWN, "error");
-	return COMMAND_RETURN_ERROR;
+	return CommandResult::ERROR;
 }
diff --git a/src/CommandError.hxx b/src/CommandError.hxx
index 507250500..183797213 100644
--- a/src/CommandError.hxx
+++ b/src/CommandError.hxx
@@ -20,19 +20,19 @@
 #ifndef MPD_COMMAND_ERROR_HXX
 #define MPD_COMMAND_ERROR_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 #include "PlaylistError.hxx"
 
 class Client;
 class Error;
 
-enum command_return
+CommandResult
 print_playlist_result(Client &client, PlaylistResult result);
 
 /**
  * Send the #Error to the client.
  */
-enum command_return
+CommandResult
 print_error(Client &client, const Error &error);
 
 #endif
diff --git a/src/command.h b/src/CommandResult.hxx
index 9ea5bb52f..4132dacb7 100644
--- a/src/command.h
+++ b/src/CommandResult.hxx
@@ -17,37 +17,45 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#ifndef MPD_COMMAND_H
-#define MPD_COMMAND_H
+#ifndef MPD_COMMAND_RESULT_HXX
+#define MPD_COMMAND_RESULT_HXX
 
-enum command_return {
+#ifdef WIN32
+#include <windows.h>
+/* damn you, windows.h! */
+#ifdef ERROR
+#undef ERROR
+#endif
+#endif
+
+enum class CommandResult {
 	/**
 	 * The command has succeeded, but the "OK" response was not
 	 * yet sent to the client.
 	 */
-	COMMAND_RETURN_OK,
+	OK,
 
 	/**
 	 * The connection is now in "idle" mode, and no response shall
 	 * be generated.
 	 */
-	COMMAND_RETURN_IDLE,
+	IDLE,
 
 	/**
 	 * There was an error.  The "ACK" response was sent to the
 	 * client.
 	 */
-	COMMAND_RETURN_ERROR,
+	ERROR,
 
 	/**
 	 * The connection to this client shall be closed.
 	 */
-	COMMAND_RETURN_CLOSE,
+	CLOSE,
 
 	/**
 	 * The MPD process shall be shut down.
 	 */
-	COMMAND_RETURN_KILL,
+	KILL,
 };
 
 #endif
diff --git a/src/DatabaseCommands.cxx b/src/DatabaseCommands.cxx
index 652b2b6d5..b86cbdae7 100644
--- a/src/DatabaseCommands.cxx
+++ b/src/DatabaseCommands.cxx
@@ -34,7 +34,7 @@
 #include <assert.h>
 #include <string.h>
 
-enum command_return
+CommandResult
 handle_lsinfo2(Client &client, int argc, char *argv[])
 {
 	const char *uri;
@@ -51,67 +51,67 @@ handle_lsinfo2(Client &client, int argc, char *argv[])
 	if (!db_selection_print(client, selection, true, error))
 		return print_error(client, error);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-static enum command_return
+static CommandResult
 handle_match(Client &client, int argc, char *argv[], bool fold_case)
 {
 	SongFilter filter;
 	if (!filter.Parse(argc - 1, argv + 1, fold_case)) {
 		command_error(client, ACK_ERROR_ARG, "incorrect arguments");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	const DatabaseSelection selection("", true, &filter);
 
 	Error error;
 	return db_selection_print(client, selection, true, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_find(Client &client, int argc, char *argv[])
 {
 	return handle_match(client, argc, argv, false);
 }
 
-enum command_return
+CommandResult
 handle_search(Client &client, int argc, char *argv[])
 {
 	return handle_match(client, argc, argv, true);
 }
 
-static enum command_return
+static CommandResult
 handle_match_add(Client &client, int argc, char *argv[], bool fold_case)
 {
 	SongFilter filter;
 	if (!filter.Parse(argc - 1, argv + 1, fold_case)) {
 		command_error(client, ACK_ERROR_ARG, "incorrect arguments");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	const DatabaseSelection selection("", true, &filter);
 	Error error;
 	return AddFromDatabase(client.partition, selection, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_findadd(Client &client, int argc, char *argv[])
 {
 	return handle_match_add(client, argc, argv, false);
 }
 
-enum command_return
+CommandResult
 handle_searchadd(Client &client, int argc, char *argv[])
 {
 	return handle_match_add(client, argc, argv, true);
 }
 
-enum command_return
+CommandResult
 handle_searchaddpl(Client &client, int argc, char *argv[])
 {
 	const char *playlist = argv[1];
@@ -119,31 +119,31 @@ handle_searchaddpl(Client &client, int argc, char *argv[])
 	SongFilter filter;
 	if (!filter.Parse(argc - 2, argv + 2, true)) {
 		command_error(client, ACK_ERROR_ARG, "incorrect arguments");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	Error error;
 	return search_add_to_playlist("", playlist, &filter, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_count(Client &client, int argc, char *argv[])
 {
 	SongFilter filter;
 	if (!filter.Parse(argc - 1, argv + 1, false)) {
 		command_error(client, ACK_ERROR_ARG, "incorrect arguments");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	Error error;
 	return  searchStatsForSongsIn(client, "", &filter, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_listall(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *directory = "";
@@ -153,24 +153,24 @@ handle_listall(Client &client, gcc_unused int argc, char *argv[])
 
 	Error error;
 	return printAllIn(client, directory, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_list(Client &client, int argc, char *argv[])
 {
 	unsigned tagType = locate_parse_type(argv[1]);
 
 	if (tagType == TAG_NUM_OF_ITEM_TYPES) {
 		command_error(client, ACK_ERROR_ARG, "\"%s\" is not known", argv[1]);
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	if (tagType == LOCATE_TAG_ANY_TYPE) {
 		command_error(client, ACK_ERROR_ARG,
 			      "\"any\" is not a valid return tag type");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	/* for compatibility with < 0.12.0 */
@@ -180,7 +180,7 @@ handle_list(Client &client, int argc, char *argv[])
 			command_error(client, ACK_ERROR_ARG,
 				      "should be \"%s\" for 3 arguments",
 				      tag_item_names[TAG_ALBUM]);
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		filter = new SongFilter((unsigned)TAG_ARTIST, argv[2]);
@@ -190,15 +190,15 @@ handle_list(Client &client, int argc, char *argv[])
 			delete filter;
 			command_error(client, ACK_ERROR_ARG,
 				      "not able to parse args");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 	} else
 		filter = nullptr;
 
 	Error error;
-	enum command_return ret =
+	CommandResult ret =
 		listAllUniqueTags(client, tagType, filter, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 
 	delete filter;
@@ -206,7 +206,7 @@ handle_list(Client &client, int argc, char *argv[])
 	return ret;
 }
 
-enum command_return
+CommandResult
 handle_listallinfo(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *directory = "";
@@ -216,6 +216,6 @@ handle_listallinfo(Client &client, gcc_unused int argc, char *argv[])
 
 	Error error;
 	return printInfoForAllIn(client, directory, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
diff --git a/src/DatabaseCommands.hxx b/src/DatabaseCommands.hxx
index 5e4130aba..c60caf246 100644
--- a/src/DatabaseCommands.hxx
+++ b/src/DatabaseCommands.hxx
@@ -20,38 +20,38 @@
 #ifndef MPD_DATABASE_COMMANDS_HXX
 #define MPD_DATABASE_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_lsinfo2(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_find(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_findadd(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_search(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_searchadd(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_searchaddpl(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_count(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_listall(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_list(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_listallinfo(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/MessageCommands.cxx b/src/MessageCommands.cxx
index 9dd22418b..7d9893e70 100644
--- a/src/MessageCommands.cxx
+++ b/src/MessageCommands.cxx
@@ -31,29 +31,29 @@
 
 #include <assert.h>
 
-enum command_return
+CommandResult
 handle_subscribe(Client &client, gcc_unused int argc, char *argv[])
 {
 	assert(argc == 2);
 
 	switch (client.Subscribe(argv[1])) {
 	case Client::SubscribeResult::OK:
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 
 	case Client::SubscribeResult::INVALID:
 		command_error(client, ACK_ERROR_ARG,
 			      "invalid channel name");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case Client::SubscribeResult::ALREADY:
 		command_error(client, ACK_ERROR_EXIST,
 			      "already subscribed to this channel");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	case Client::SubscribeResult::FULL:
 		command_error(client, ACK_ERROR_EXIST,
 			      "subscription list is full");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	/* unreachable */
@@ -61,21 +61,21 @@ handle_subscribe(Client &client, gcc_unused int argc, char *argv[])
 	gcc_unreachable();
 }
 
-enum command_return
+CommandResult
 handle_unsubscribe(Client &client, gcc_unused int argc, char *argv[])
 {
 	assert(argc == 2);
 
 	if (client.Unsubscribe(argv[1]))
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	else {
 		command_error(client, ACK_ERROR_NO_EXIST,
 			      "not subscribed to this channel");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 }
 
-enum command_return
+CommandResult
 handle_channels(Client &client,
 		gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -89,10 +89,10 @@ handle_channels(Client &client,
 	for (const auto &channel : channels)
 		client_printf(client, "channel: %s\n", channel.c_str());
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_read_messages(Client &client,
 		     gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -106,10 +106,10 @@ handle_read_messages(Client &client,
 		client.messages.pop_front();
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_send_message(Client &client,
 		    gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -118,7 +118,7 @@ handle_send_message(Client &client,
 	if (!client_message_valid_channel_name(argv[1])) {
 		command_error(client, ACK_ERROR_ARG,
 			      "invalid channel name");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	bool sent = false;
@@ -128,10 +128,10 @@ handle_send_message(Client &client,
 			sent = true;
 
 	if (sent)
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	else {
 		command_error(client, ACK_ERROR_NO_EXIST,
 			      "nobody is subscribed to this channel");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 }
diff --git a/src/MessageCommands.hxx b/src/MessageCommands.hxx
index 150e0a2a2..921b20c94 100644
--- a/src/MessageCommands.hxx
+++ b/src/MessageCommands.hxx
@@ -20,23 +20,23 @@
 #ifndef MPD_MESSAGE_COMMANDS_HXX
 #define MPD_MESSAGE_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_subscribe(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_unsubscribe(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_channels(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_read_messages(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_send_message(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/OtherCommands.cxx b/src/OtherCommands.cxx
index 3e1e6fdd4..1291caf4e 100644
--- a/src/OtherCommands.cxx
+++ b/src/OtherCommands.cxx
@@ -63,47 +63,47 @@ print_spl_list(Client &client, const PlaylistVector &list)
 	}
 }
 
-enum command_return
+CommandResult
 handle_urlhandlers(Client &client,
 		   gcc_unused int argc, gcc_unused char *argv[])
 {
 	if (client.IsLocal())
 		client_puts(client, "handler: file://\n");
 	print_supported_uri_schemes(client);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_decoders(Client &client,
 		gcc_unused int argc, gcc_unused char *argv[])
 {
 	decoder_list_print(client);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_tagtypes(Client &client,
 		gcc_unused int argc, gcc_unused char *argv[])
 {
 	tag_print_types(client);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_kill(gcc_unused Client &client,
 	    gcc_unused int argc, gcc_unused char *argv[])
 {
-	return COMMAND_RETURN_KILL;
+	return CommandResult::KILL;
 }
 
-enum command_return
+CommandResult
 handle_close(gcc_unused Client &client,
 	     gcc_unused int argc, gcc_unused char *argv[])
 {
-	return COMMAND_RETURN_CLOSE;
+	return CommandResult::CLOSE;
 }
 
-enum command_return
+CommandResult
 handle_lsinfo(Client &client, int argc, char *argv[])
 {
 	const char *uri;
@@ -122,7 +122,7 @@ handle_lsinfo(Client &client, int argc, char *argv[])
 		if (path_fs.IsNull()) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "unsupported file name");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		Error error;
@@ -133,16 +133,16 @@ handle_lsinfo(Client &client, int argc, char *argv[])
 		if (song == NULL) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "No such file");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		song_print_info(client, *song);
 		song->Free();
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	}
 
-	enum command_return result = handle_lsinfo2(client, argc, argv);
-	if (result != COMMAND_RETURN_OK)
+	CommandResult result = handle_lsinfo2(client, argc, argv);
+	if (result != CommandResult::OK)
 		return result;
 
 	if (isRootDirectory(uri)) {
@@ -151,10 +151,10 @@ handle_lsinfo(Client &client, int argc, char *argv[])
 		print_spl_list(client, list);
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_update(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *path = "";
@@ -170,22 +170,22 @@ handle_update(Client &client, gcc_unused int argc, char *argv[])
 		else if (!uri_safe_local(path)) {
 			command_error(client, ACK_ERROR_ARG,
 				      "Malformed path");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 	}
 
 	ret = update_enqueue(path, false);
 	if (ret > 0) {
 		client_printf(client, "updating_db: %i\n", ret);
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	} else {
 		command_error(client, ACK_ERROR_UPDATE_ALREADY,
 			      "already updating");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 }
 
-enum command_return
+CommandResult
 handle_rescan(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *path = "";
@@ -198,93 +198,93 @@ handle_rescan(Client &client, gcc_unused int argc, char *argv[])
 		if (!uri_safe_local(path)) {
 			command_error(client, ACK_ERROR_ARG,
 				      "Malformed path");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 	}
 
 	ret = update_enqueue(path, true);
 	if (ret > 0) {
 		client_printf(client, "updating_db: %i\n", ret);
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	} else {
 		command_error(client, ACK_ERROR_UPDATE_ALREADY,
 			      "already updating");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 }
 
-enum command_return
+CommandResult
 handle_setvol(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned level;
 	bool success;
 
 	if (!check_unsigned(client, &level, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	if (level > 100) {
 		command_error(client, ACK_ERROR_ARG, "Invalid volume value");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	success = volume_level_change(level);
 	if (!success) {
 		command_error(client, ACK_ERROR_SYSTEM,
 			      "problems setting volume");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_stats(Client &client,
 	     gcc_unused int argc, gcc_unused char *argv[])
 {
 	stats_print(client);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_ping(gcc_unused Client &client,
 	    gcc_unused int argc, gcc_unused char *argv[])
 {
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_password(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned permission = 0;
 
 	if (getPermissionFromPassword(argv[1], &permission) < 0) {
 		command_error(client, ACK_ERROR_PASSWORD, "incorrect password");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	client.SetPermission(permission);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_config(Client &client,
 	      gcc_unused int argc, gcc_unused char *argv[])
 {
 	if (!client.IsLocal()) {
 		command_error(client, ACK_ERROR_PERMISSION,
 			      "Command only permitted to local clients");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	const char *path = mapper_get_music_directory_utf8();
 	if (path != NULL)
 		client_printf(client, "music_directory: %s\n", path);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_idle(Client &client,
 	    gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -311,5 +311,5 @@ handle_idle(Client &client,
 	/* enable "idle" mode on this client */
 	client.IdleWait(flags);
 
-	return COMMAND_RETURN_IDLE;
+	return CommandResult::IDLE;
 }
diff --git a/src/OtherCommands.hxx b/src/OtherCommands.hxx
index b0968d302..fe3e145c4 100644
--- a/src/OtherCommands.hxx
+++ b/src/OtherCommands.hxx
@@ -20,50 +20,50 @@
 #ifndef MPD_OTHER_COMMANDS_HXX
 #define MPD_OTHER_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_urlhandlers(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_decoders(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_tagtypes(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_kill(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_close(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_lsinfo(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_update(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_rescan(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_setvol(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_stats(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_ping(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_password(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_config(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_idle(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/OutputCommands.cxx b/src/OutputCommands.cxx
index ef35ba8ec..8d6ea8ed7 100644
--- a/src/OutputCommands.cxx
+++ b/src/OutputCommands.cxx
@@ -26,65 +26,65 @@
 
 #include <string.h>
 
-enum command_return
+CommandResult
 handle_enableoutput(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned device;
 	bool ret;
 
 	if (!check_unsigned(client, &device, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	ret = audio_output_enable_index(device);
 	if (!ret) {
 		command_error(client, ACK_ERROR_NO_EXIST,
 			      "No such audio output");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_disableoutput(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned device;
 	bool ret;
 
 	if (!check_unsigned(client, &device, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	ret = audio_output_disable_index(device);
 	if (!ret) {
 		command_error(client, ACK_ERROR_NO_EXIST,
 			      "No such audio output");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_toggleoutput(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned device;
 	if (!check_unsigned(client, &device, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	if (!audio_output_toggle_index(device)) {
 		command_error(client, ACK_ERROR_NO_EXIST,
 			      "No such audio output");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_devices(Client &client,
 	       gcc_unused int argc, gcc_unused char *argv[])
 {
 	printAudioDevices(client);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
diff --git a/src/OutputCommands.hxx b/src/OutputCommands.hxx
index c0d3b9030..ac3c0211a 100644
--- a/src/OutputCommands.hxx
+++ b/src/OutputCommands.hxx
@@ -20,20 +20,20 @@
 #ifndef MPD_OUTPUT_COMMANDS_HXX
 #define MPD_OUTPUT_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_enableoutput(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_disableoutput(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_toggleoutput(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_devices(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/PlayerCommands.cxx b/src/PlayerCommands.cxx
index 9bc162ea7..d30bde273 100644
--- a/src/PlayerCommands.cxx
+++ b/src/PlayerCommands.cxx
@@ -52,62 +52,62 @@
 #define COMMAND_STATUS_AUDIO		"audio"
 #define COMMAND_STATUS_UPDATING_DB	"updating_db"
 
-enum command_return
+CommandResult
 handle_play(Client &client, int argc, char *argv[])
 {
 	int song = -1;
 
 	if (argc == 2 && !check_int(client, &song, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	PlaylistResult result = client.partition.PlayPosition(song);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_playid(Client &client, int argc, char *argv[])
 {
 	int id = -1;
 
 	if (argc == 2 && !check_int(client, &id, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result = client.partition.PlayId(id);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_stop(Client &client,
 	    gcc_unused int argc, gcc_unused char *argv[])
 {
 	client.partition.Stop();
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_currentsong(Client &client,
 		   gcc_unused int argc, gcc_unused char *argv[])
 {
 	playlist_print_current(client, client.playlist);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_pause(Client &client,
 	     int argc, char *argv[])
 {
 	if (argc == 2) {
 		bool pause_flag;
 		if (!check_bool(client, &pause_flag, argv[1]))
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 
 		client.player_control.SetPause(pause_flag);
 	} else
 		client.player_control.Pause();
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_status(Client &client,
 	      gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -202,10 +202,10 @@ handle_status(Client &client,
 			      song, playlist.PositionToId(song));
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_next(Client &client,
 	    gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -219,170 +219,170 @@ handle_next(Client &client,
 	client.partition.PlayNext();
 
 	playlist.queue.single = single;
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_previous(Client &client,
 		gcc_unused int argc, gcc_unused char *argv[])
 {
 	client.partition.PlayPrevious();
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_repeat(Client &client, gcc_unused int argc, char *argv[])
 {
 	bool status;
 	if (!check_bool(client, &status, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	client.partition.SetRepeat(status);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_single(Client &client, gcc_unused int argc, char *argv[])
 {
 	bool status;
 	if (!check_bool(client, &status, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	client.partition.SetSingle(status);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_consume(Client &client, gcc_unused int argc, char *argv[])
 {
 	bool status;
 	if (!check_bool(client, &status, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	client.partition.SetConsume(status);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_random(Client &client, gcc_unused int argc, char *argv[])
 {
 	bool status;
 	if (!check_bool(client, &status, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	client.partition.SetRandom(status);
 	audio_output_all_set_replay_gain_mode(replay_gain_get_real_mode(client.partition.GetRandom()));
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_clearerror(gcc_unused Client &client,
 		  gcc_unused int argc, gcc_unused char *argv[])
 {
 	client.player_control.ClearError();
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_seek(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned song, seek_time;
 
 	if (!check_unsigned(client, &song, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_unsigned(client, &seek_time, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result =
 		client.partition.SeekSongPosition(song, seek_time);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_seekid(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned id, seek_time;
 
 	if (!check_unsigned(client, &id, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_unsigned(client, &seek_time, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result =
 		client.partition.SeekSongId(id, seek_time);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_seekcur(Client &client, gcc_unused int argc, char *argv[])
 {
 	const char *p = argv[1];
 	bool relative = *p == '+' || *p == '-';
 	int seek_time;
 	if (!check_int(client, &seek_time, p))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result =
 		client.partition.SeekCurrent(seek_time, relative);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_crossfade(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned xfade_time;
 
 	if (!check_unsigned(client, &xfade_time, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	client.player_control.SetCrossFade(xfade_time);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_mixrampdb(Client &client, gcc_unused int argc, char *argv[])
 {
 	float db;
 
 	if (!check_float(client, &db, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	client.player_control.SetMixRampDb(db);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_mixrampdelay(Client &client, gcc_unused int argc, char *argv[])
 {
 	float delay_secs;
 
 	if (!check_float(client, &delay_secs, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	client.player_control.SetMixRampDelay(delay_secs);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_replay_gain_mode(Client &client,
 			gcc_unused int argc, char *argv[])
 {
 	if (!replay_gain_set_mode_string(argv[1])) {
 		command_error(client, ACK_ERROR_ARG,
 			      "Unrecognized replay gain mode");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	audio_output_all_set_replay_gain_mode(replay_gain_get_real_mode(client.playlist.queue.random));
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_replay_gain_status(Client &client,
 			  gcc_unused int argc, gcc_unused char *argv[])
 {
 	client_printf(client, "replay_gain_mode: %s\n",
 		      replay_gain_get_mode_string());
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
diff --git a/src/PlayerCommands.hxx b/src/PlayerCommands.hxx
index 6bef71a01..c201c7a57 100644
--- a/src/PlayerCommands.hxx
+++ b/src/PlayerCommands.hxx
@@ -20,71 +20,71 @@
 #ifndef MPD_PLAYER_COMMANDS_HXX
 #define MPD_PLAYER_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_play(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_stop(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_currentsong(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_pause(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_status(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_next(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_previous(Client &client, int argc, char *avg[]);
 
-enum command_return
+CommandResult
 handle_repeat(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_single(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_consume(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_random(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_clearerror(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_seek(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_seekid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_seekcur(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_crossfade(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_mixrampdb(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_mixrampdelay(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_replay_gain_mode(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_replay_gain_status(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/PlaylistCommands.cxx b/src/PlaylistCommands.cxx
index 02c21e01f..d178fa097 100644
--- a/src/PlaylistCommands.cxx
+++ b/src/PlaylistCommands.cxx
@@ -49,14 +49,14 @@ print_spl_list(Client &client, const PlaylistVector &list)
 	}
 }
 
-enum command_return
+CommandResult
 handle_save(Client &client, gcc_unused int argc, char *argv[])
 {
 	PlaylistResult result = spl_save_playlist(argv[1], client.playlist);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_load(Client &client, int argc, char *argv[])
 {
 	unsigned start_index, end_index;
@@ -65,7 +65,7 @@ handle_load(Client &client, int argc, char *argv[])
 		start_index = 0;
 		end_index = unsigned(-1);
 	} else if (!check_range(client, &start_index, &end_index, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	const PlaylistResult result =
 		playlist_open_into_queue(argv[1],
@@ -79,7 +79,7 @@ handle_load(Client &client, int argc, char *argv[])
 	if (playlist_load_spl(client.playlist, client.player_control,
 			      argv[1], start_index, end_index,
 			      error))
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 
 	if (error.IsDomain(playlist_domain) &&
 	    PlaylistResult(error.GetCode()) == PlaylistResult::BAD_NAME) {
@@ -95,91 +95,91 @@ handle_load(Client &client, int argc, char *argv[])
 	return print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_listplaylist(Client &client, gcc_unused int argc, char *argv[])
 {
 	if (playlist_file_print(client, argv[1], false))
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 
 	Error error;
 	return spl_print(client, argv[1], false, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_listplaylistinfo(Client &client,
 			gcc_unused int argc, char *argv[])
 {
 	if (playlist_file_print(client, argv[1], true))
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 
 	Error error;
 	return spl_print(client, argv[1], true, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_rm(Client &client, gcc_unused int argc, char *argv[])
 {
 	Error error;
 	return spl_delete(argv[1], error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_rename(Client &client, gcc_unused int argc, char *argv[])
 {
 	Error error;
 	return spl_rename(argv[1], argv[2], error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_playlistdelete(Client &client,
 		      gcc_unused int argc, char *argv[]) {
 	char *playlist = argv[1];
 	unsigned from;
 
 	if (!check_unsigned(client, &from, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	Error error;
 	return spl_remove_index(playlist, from, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_playlistmove(Client &client, gcc_unused int argc, char *argv[])
 {
 	char *playlist = argv[1];
 	unsigned from, to;
 
 	if (!check_unsigned(client, &from, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_unsigned(client, &to, argv[3]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	Error error;
 	return spl_move_index(playlist, from, to, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_playlistclear(Client &client, gcc_unused int argc, char *argv[])
 {
 	Error error;
 	return spl_clear(argv[1], error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_playlistadd(Client &client, gcc_unused int argc, char *argv[])
 {
 	char *playlist = argv[1];
@@ -191,7 +191,7 @@ handle_playlistadd(Client &client, gcc_unused int argc, char *argv[])
 		if (!uri_supported_scheme(uri)) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "unsupported URI scheme");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		success = spl_append_uri(uri, playlist, error);
@@ -202,13 +202,13 @@ handle_playlistadd(Client &client, gcc_unused int argc, char *argv[])
 	if (!success && !error.IsDefined()) {
 		command_error(client, ACK_ERROR_NO_EXIST,
 			      "directory or file not found");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
-	return success ? COMMAND_RETURN_OK : print_error(client, error);
+	return success ? CommandResult::OK : print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_listplaylists(Client &client,
 		     gcc_unused int argc, gcc_unused char *argv[])
 {
@@ -218,5 +218,5 @@ handle_listplaylists(Client &client,
 		return print_error(client, error);
 
 	print_spl_list(client, list);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
diff --git a/src/PlaylistCommands.hxx b/src/PlaylistCommands.hxx
index a34ee6b32..786f8b89f 100644
--- a/src/PlaylistCommands.hxx
+++ b/src/PlaylistCommands.hxx
@@ -20,41 +20,41 @@
 #ifndef MPD_PLAYLIST_COMMANDS_HXX
 #define MPD_PLAYLIST_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_save(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_load(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_listplaylist(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_listplaylistinfo(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_rm(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_rename(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistdelete(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistmove(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistclear(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistadd(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_listplaylists(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/QueueCommands.cxx b/src/QueueCommands.cxx
index 92355bdff..a21eb75f0 100644
--- a/src/QueueCommands.cxx
+++ b/src/QueueCommands.cxx
@@ -39,7 +39,7 @@
 
 #include <string.h>
 
-enum command_return
+CommandResult
 handle_add(Client &client, gcc_unused int argc, char *argv[])
 {
 	char *uri = argv[1];
@@ -52,7 +52,7 @@ handle_add(Client &client, gcc_unused int argc, char *argv[])
 		if (path_fs.IsNull()) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "unsupported file name");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		Error error;
@@ -67,7 +67,7 @@ handle_add(Client &client, gcc_unused int argc, char *argv[])
 		if (!uri_supported_scheme(uri)) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "unsupported URI scheme");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		result = client.partition.AppendURI(uri);
@@ -77,11 +77,11 @@ handle_add(Client &client, gcc_unused int argc, char *argv[])
 	const DatabaseSelection selection(uri, true);
 	Error error;
 	return AddFromDatabase(client.partition, selection, error)
-		? COMMAND_RETURN_OK
+		? CommandResult::OK
 		: print_error(client, error);
 }
 
-enum command_return
+CommandResult
 handle_addid(Client &client, int argc, char *argv[])
 {
 	char *uri = argv[1];
@@ -95,7 +95,7 @@ handle_addid(Client &client, int argc, char *argv[])
 		if (path_fs.IsNull()) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "unsupported file name");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		Error error;
@@ -107,7 +107,7 @@ handle_addid(Client &client, int argc, char *argv[])
 		if (uri_has_scheme(uri) && !uri_supported_scheme(uri)) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "unsupported URI scheme");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		result = client.partition.AppendURI(uri, &added_id);
@@ -119,10 +119,10 @@ handle_addid(Client &client, int argc, char *argv[])
 	if (argc == 3) {
 		unsigned to;
 		if (!check_unsigned(client, &to, argv[2]))
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		result = client.partition.MoveId(added_id, to);
 		if (result != PlaylistResult::SUCCESS) {
-			enum command_return ret =
+			CommandResult ret =
 				print_playlist_result(client, result);
 			client.partition.DeleteId(added_id);
 			return ret;
@@ -130,109 +130,109 @@ handle_addid(Client &client, int argc, char *argv[])
 	}
 
 	client_printf(client, "Id: %u\n", added_id);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_delete(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned start, end;
 
 	if (!check_range(client, &start, &end, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result = client.partition.DeleteRange(start, end);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_deleteid(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned id;
 
 	if (!check_unsigned(client, &id, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result = client.partition.DeleteId(id);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_playlist(Client &client,
 		gcc_unused int argc, gcc_unused char *argv[])
 {
 	playlist_print_uris(client, client.playlist);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_shuffle(gcc_unused Client &client,
 	       gcc_unused int argc, gcc_unused char *argv[])
 {
 	unsigned start = 0, end = client.playlist.queue.GetLength();
 	if (argc == 2 && !check_range(client, &start, &end, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	client.partition.Shuffle(start, end);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_clear(gcc_unused Client &client,
 	     gcc_unused int argc, gcc_unused char *argv[])
 {
 	client.partition.ClearQueue();
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_plchanges(Client &client, gcc_unused int argc, char *argv[])
 {
 	uint32_t version;
 
 	if (!check_uint32(client, &version, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	playlist_print_changes_info(client, client.playlist, version);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_plchangesposid(Client &client, gcc_unused int argc, char *argv[])
 {
 	uint32_t version;
 
 	if (!check_uint32(client, &version, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	playlist_print_changes_position(client, client.playlist, version);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_playlistinfo(Client &client, int argc, char *argv[])
 {
 	unsigned start = 0, end = std::numeric_limits<unsigned>::max();
 	bool ret;
 
 	if (argc == 2 && !check_range(client, &start, &end, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	ret = playlist_print_info(client, client.playlist, start, end);
 	if (!ret)
 		return print_playlist_result(client,
 					     PlaylistResult::BAD_RANGE);
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_playlistid(Client &client, int argc, char *argv[])
 {
 	if (argc >= 2) {
 		unsigned id;
 		if (!check_unsigned(client, &id, argv[1]))
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 
 		bool ret = playlist_print_id(client, client.playlist, id);
 		if (!ret)
@@ -243,54 +243,54 @@ handle_playlistid(Client &client, int argc, char *argv[])
 				    0, std::numeric_limits<unsigned>::max());
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-static enum command_return
+static CommandResult
 handle_playlist_match(Client &client, int argc, char *argv[],
 		      bool fold_case)
 {
 	SongFilter filter;
 	if (!filter.Parse(argc - 1, argv + 1, fold_case)) {
 		command_error(client, ACK_ERROR_ARG, "incorrect arguments");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	playlist_print_find(client, client.playlist, filter);
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_playlistfind(Client &client, int argc, char *argv[])
 {
 	return handle_playlist_match(client, argc, argv, false);
 }
 
-enum command_return
+CommandResult
 handle_playlistsearch(Client &client, int argc, char *argv[])
 {
 	return handle_playlist_match(client, argc, argv, true);
 }
 
-enum command_return
+CommandResult
 handle_prio(Client &client, int argc, char *argv[])
 {
 	unsigned priority;
 
 	if (!check_unsigned(client, &priority, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	if (priority > 0xff) {
 		command_error(client, ACK_ERROR_ARG,
 			      "Priority out of range: %s", argv[1]);
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	for (int i = 2; i < argc; ++i) {
 		unsigned start_position, end_position;
 		if (!check_range(client, &start_position, &end_position,
 				 argv[i]))
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 
 		PlaylistResult result =
 			client.partition.SetPriorityRange(start_position,
@@ -300,27 +300,27 @@ handle_prio(Client &client, int argc, char *argv[])
 			return print_playlist_result(client, result);
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_prioid(Client &client, int argc, char *argv[])
 {
 	unsigned priority;
 
 	if (!check_unsigned(client, &priority, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	if (priority > 0xff) {
 		command_error(client, ACK_ERROR_ARG,
 			      "Priority out of range: %s", argv[1]);
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	for (int i = 2; i < argc; ++i) {
 		unsigned song_id;
 		if (!check_unsigned(client, &song_id, argv[i]))
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 
 		PlaylistResult result =
 			client.partition.SetPriorityId(song_id, priority);
@@ -328,63 +328,63 @@ handle_prioid(Client &client, int argc, char *argv[])
 			return print_playlist_result(client, result);
 	}
 
-	return COMMAND_RETURN_OK;
+	return CommandResult::OK;
 }
 
-enum command_return
+CommandResult
 handle_move(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned start, end;
 	int to;
 
 	if (!check_range(client, &start, &end, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_int(client, &to, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result =
 		client.partition.MoveRange(start, end, to);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_moveid(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned id;
 	int to;
 
 	if (!check_unsigned(client, &id, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_int(client, &to, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	PlaylistResult result = client.partition.MoveId(id, to);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_swap(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned song1, song2;
 
 	if (!check_unsigned(client, &song1, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_unsigned(client, &song2, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result =
 		client.partition.SwapPositions(song1, song2);
 	return print_playlist_result(client, result);
 }
 
-enum command_return
+CommandResult
 handle_swapid(Client &client, gcc_unused int argc, char *argv[])
 {
 	unsigned id1, id2;
 
 	if (!check_unsigned(client, &id1, argv[1]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	if (!check_unsigned(client, &id2, argv[2]))
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 
 	PlaylistResult result = client.partition.SwapIds(id1, id2);
 	return print_playlist_result(client, result);
diff --git a/src/QueueCommands.hxx b/src/QueueCommands.hxx
index 09b489212..3beb28e52 100644
--- a/src/QueueCommands.hxx
+++ b/src/QueueCommands.hxx
@@ -20,65 +20,65 @@
 #ifndef MPD_QUEUE_COMMANDS_HXX
 #define MPD_QUEUE_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_add(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_addid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_delete(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_deleteid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlist(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_shuffle(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_clear(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_plchanges(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_plchangesposid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistinfo(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistfind(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_playlistsearch(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_prio(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_prioid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_move(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_moveid(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_swap(Client &client, int argc, char *argv[]);
 
-enum command_return
+CommandResult
 handle_swapid(Client &client, int argc, char *argv[]);
 
 #endif
diff --git a/src/StickerCommands.cxx b/src/StickerCommands.cxx
index 6688c0820..cbd371c8f 100644
--- a/src/StickerCommands.cxx
+++ b/src/StickerCommands.cxx
@@ -51,7 +51,7 @@ sticker_song_find_print_cb(Song &song, const char *value,
 	sticker_print_value(data->client, data->name, value);
 }
 
-static enum command_return
+static CommandResult
 handle_sticker_song(Client &client, int argc, char *argv[])
 {
 	Error error;
@@ -70,12 +70,12 @@ handle_sticker_song(Client &client, int argc, char *argv[])
 		if (value.empty()) {
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "no such sticker");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		sticker_print_value(client, argv[4], value.c_str());
 
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	/* list song song_id */
 	} else if (argc == 4 && strcmp(argv[1], "list") == 0) {
 		Song *song = db->GetSong(argv[3], error);
@@ -89,7 +89,7 @@ handle_sticker_song(Client &client, int argc, char *argv[])
 			sticker_free(sticker);
 		}
 
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	/* set song song_id id key */
 	} else if (argc == 6 && strcmp(argv[1], "set") == 0) {
 		Song *song = db->GetSong(argv[3], error);
@@ -101,10 +101,10 @@ handle_sticker_song(Client &client, int argc, char *argv[])
 		if (!ret) {
 			command_error(client, ACK_ERROR_SYSTEM,
 				      "failed to set sticker value");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	/* delete song song_id [key] */
 	} else if ((argc == 4 || argc == 5) &&
 		   strcmp(argv[1], "delete") == 0) {
@@ -119,10 +119,10 @@ handle_sticker_song(Client &client, int argc, char *argv[])
 		if (!ret) {
 			command_error(client, ACK_ERROR_SYSTEM,
 				      "no such sticker");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	/* find song dir key */
 	} else if (argc == 5 && strcmp(argv[1], "find") == 0) {
 		/* "sticker find song a/directory name" */
@@ -138,7 +138,7 @@ handle_sticker_song(Client &client, int argc, char *argv[])
 			db_unlock();
 			command_error(client, ACK_ERROR_NO_EXIST,
 				      "no such directory");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
 		success = sticker_song_find(*directory, data.name,
@@ -147,17 +147,17 @@ handle_sticker_song(Client &client, int argc, char *argv[])
 		if (!success) {
 			command_error(client, ACK_ERROR_SYSTEM,
 				      "failed to set search sticker database");
-			return COMMAND_RETURN_ERROR;
+			return CommandResult::ERROR;
 		}
 
-		return COMMAND_RETURN_OK;
+		return CommandResult::OK;
 	} else {
 		command_error(client, ACK_ERROR_ARG, "bad request");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 }
 
-enum command_return
+CommandResult
 handle_sticker(Client &client, int argc, char *argv[])
 {
 	assert(argc >= 4);
@@ -165,7 +165,7 @@ handle_sticker(Client &client, int argc, char *argv[])
 	if (!sticker_enabled()) {
 		command_error(client, ACK_ERROR_UNKNOWN,
 			      "sticker database is disabled");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 
 	if (strcmp(argv[2], "song") == 0)
@@ -173,6 +173,6 @@ handle_sticker(Client &client, int argc, char *argv[])
 	else {
 		command_error(client, ACK_ERROR_ARG,
 			      "unknown sticker domain");
-		return COMMAND_RETURN_ERROR;
+		return CommandResult::ERROR;
 	}
 }
diff --git a/src/StickerCommands.hxx b/src/StickerCommands.hxx
index 0aaa74de0..fb91a8ad3 100644
--- a/src/StickerCommands.hxx
+++ b/src/StickerCommands.hxx
@@ -20,11 +20,11 @@
 #ifndef MPD_STICKER_COMMANDS_HXX
 #define MPD_STICKER_COMMANDS_HXX
 
-#include "command.h"
+#include "CommandResult.hxx"
 
 class Client;
 
-enum command_return
+CommandResult
 handle_sticker(Client &client, int argc, char *argv[]);
 
 #endif